阅读说明：本技术 一种水分散石墨烯的制备方法及其应用 (Preparation method and application of water dispersible graphene ) 是由 付少海 仇明慧 王冬 李敏 张丽萍 刘明明 田安丽 于 2019-08-27 设计创作，主要内容包括：本发明公开了一种水分散石墨烯的制备方法及其应用,属于石墨烯/聚合物复合材料技术领域。本发明以1-烯丙氧基-3-(4-壬基苯酚)-2-丙醇聚氧乙烯(10)醚硫酸铵的水溶液为电解质,石墨片为阳极、金属棒为阴极,电解剥离石墨片,得到水分散的石墨烯。所得石墨烯在水中的分散性较好,能够与备聚乙烯醇共混制备聚乙烯醇/石墨烯复合材料,提高了聚乙烯醇材料的力学性能和阻燃性能,在纺织、医药工业、食品工业、建筑、化学工业领域具有广阔的应用前景。(The invention discloses a preparation method and application of water dispersible graphene, and belongs to the technical field of graphene/polymer composite materials. The method takes 1-allyloxy-3- (4-nonylphenol) -2-propanol polyoxyethylene (10) ether ammonium sulfate aqueous solution as electrolyte, graphite flake as anode and metal bar as cathode, and strips the graphite flake through electrolysis to obtain the water-dispersed graphene. The obtained graphene has good dispersibility in water, can be blended with prepared polyvinyl alcohol to prepare a polyvinyl alcohol/graphene composite material, improves the mechanical property and flame retardant property of the polyvinyl alcohol material, and has wide application prospects in the fields of textiles, medical industry, food industry, construction and chemical industry.)

1. The preparation method of the water dispersible graphene is characterized in that 1-allyloxy-3- (4-nonylphenol) -2-propanol polyoxyethylene (10) ether ammonium sulfate is loaded on the surface of graphene to prepare the water dispersible graphene.

2. The method of claim 1, wherein the method is used for electrochemically loading 1-allyloxy-3- (4-nonylphenol) -2-propanol polyoxyethylene (10) ether ammonium sulfate on the surface of graphene, and comprises the following steps: and (3) electrolyzing by taking the aqueous solution of 1-allyloxy-3- (4-nonylphenol) -2-propanol polyoxyethylene (10) ether ammonium sulfate as electrolyte, a graphite sheet as an anode and a metal bar as a cathode to obtain the water-dispersible graphene.

3. The process according to claim 1 or 2, characterized in that the concentration of the aqueous solution of ammonium 1-allyloxy-3- (4-nonylphenol) -2-propanol polyoxyethylene (10) ethersulfate is from 5g/L to 30 g/L.

4. The method according to claim 2, wherein the electrolysis is carried out under a DC voltage of 5V to 20V.

5. A method according to any one of claims 2 to 4, wherein the graphite sheets are graphite sheets having a thickness of from 0.3mm to 1 mm.

6. The method of any one of claims 1 to 4, wherein the graphene is prepared by water dispersion.

7. A polyvinyl alcohol/graphene composite material, which is prepared by blending the water dispersible graphene according to claim 6 with polyvinyl alcohol.

8. The composite material of claim 7, wherein the mass ratio of the polyvinyl alcohol to the water dispersible graphene is 100 (0.1-3).

9. A building or textile material, characterized in that it comprises a composite material according to claim 7 or 8.

10. Use of the polyvinyl alcohol/graphene composite material according to claim 7 or 8 in the fields of textile, medical industry, food industry, construction, wood processing, chemical industry.

Technical Field

The invention belongs to the technical field of graphene/polymer composite materials, and particularly relates to a preparation method and application of water dispersible graphene.

Background

Polyvinyl alcohol is a water-soluble high molecular polymer, has a large number of hydroxyl groups on the main chain, has a regular structure, has a series of advantages of good film-forming property, biocompatibility, biodegradability, low price and the like, and becomes a water-soluble polymer material which is widely applied to the fields of textile, medical industry, food industry, building, wood processing, chemical industry and the like and has huge development potential. However, polyvinyl alcohol is extremely easy to burn, the Limiting Oxygen Index (LOI) is only 19%, and simultaneously, with the development of material science, the chemical stability, thermal property, mechanical property and the like of a material prepared by singly using polyvinyl alcohol are not enough to meet the requirements of people. Therefore, research and development and production of polyvinyl alcohol with excellent mechanical property and flame retardant property are of great significance, and the improvement of the mechanical property and the flame retardant property can enable the polyvinyl alcohol material to have wider application prospect.

The graphene is of a two-dimensional honeycomb crystal structure formed by tightly stacking single-layer carbon atoms, and sigma bonds in the carbon atom layers are combined in the surface structure of the graphene, so that the graphene has extremely excellent mechanical properties, the tensile strength of the graphene can reach 125GPa, the modulus of the graphene can reach 1.1TPa, and the graphene is taken as a reinforcing phase, so that the graphene has great prospect and value in the field of composite materials. Meanwhile, the graphene-based material has excellent thermal conductivity (thermal conductivity of 5.3 × 10)³W/(m.K)) and good gas barrier properties. Therefore, the unique two-dimensional carbon atom lamellar structure can be used as a good flame retardant to improve the flame retardant property of the polymer material. However, graphene and polyvinyl alcohol are inorganic and organic, respectively, and thus have poor compatibility. In addition, strong van der waals forces exist between graphene sheets, which can cause the graphene sheets to be in contact with each otherAgglomeration is easy to occur in the process of compounding polyvinyl alcohol. So that the performance of the polyvinyl alcohol material is not obviously improved or even is reduced.

In order to further study graphene and fully exert its excellent properties, it is important to improve the dispersibility of graphene. In order to improve the dispersibility of graphene in a polyvinyl alcohol matrix, researchers generally adopt a redox method to prepare graphene oxide, because the method can enable basal planes and edges of the graphene to contain a large number of oxygen-containing functional groups, and the hydrophilic functional groups enable the graphene to be highly dispersed in an aqueous medium. Meanwhile, the oxygen-containing functional groups can form hydrogen bonds with the lateral group hydroxyl of the polyvinyl alcohol, and the mixed solution can form stable and uniform solution. As disclosed in patent cn201510423397.x, a polyvinyl alcohol/graphene nanofiber material and a preparation method thereof are disclosed, comprising the following steps: firstly preparing graphene oxide by using an improved Hummer, then dissolving polyvinyl alcohol in deionized water, then dissolving the polyvinyl alcohol in an aqueous solution of the graphene oxide, carrying out ultrasonic treatment and stirring to obtain a polyvinyl alcohol/graphene uniform mixed solution, then adding an oxidation free radical scavenger into the polyvinyl alcohol/graphene uniform mixed solution, stirring and reducing the graphene oxide under high-energy ionizing radiation, and finally preparing the polyvinyl alcohol/graphene composite nanofiber material by adopting an electrostatic spinning mode. The tensile strength of the prepared polyvinyl alcohol/graphene composite nanofiber reaches 20.7-23.9 MPa. Patent CN201510481021.4 discloses a glycine modified graphene oxide, polyvinyl alcohol halogen-free flame retardant material and a preparation method thereof, comprising the following steps: firstly, preparing graphene oxide by using Hummer, then adding aminoacetic acid into graphene oxide dispersion liquid to prepare aminoacetic acid modified graphene oxide, finally adding the aminoacetic acid modified graphene oxide dispersion liquid into polyvinyl alcohol solution, uniformly stirring, then adding magnesium-aluminum type layered double hydroxide dispersion liquid, uniformly stirring, and drying to obtain the polyvinyl alcohol halogen-free flame retardant material. The limit oxygen index of the prepared polyvinyl alcohol halogen-free flame-retardant material can reach 35.7 percent at most.

In conclusion, the graphene oxide prepared by the oxidation method improves the dispersibility of the graphene in the polyvinyl alcohol matrix, so that the mechanical property and the flame retardant property of the polyvinyl alcohol are improved, but the graphene prepared by the oxidation method has more defects, cannot be completely reduced, uses a lot of strong acid in the reaction process, and does not meet the requirement of green production; in addition, the graphene oxide is further modified, so that the defects of long process flow, low economic benefit and the like are overcome. Therefore, the development of a low-defect and pollution-free flame retardant functionalized graphene is urgently needed in the market.

Disclosure of Invention

Aiming at the defects and shortcomings of the prior art, the invention provides a simple, environment-friendly and easy-to-operate electrochemical method, and the water-dispersible graphene is prepared by intercalation, oxidation, stripping and modification of graphite flakes. The method avoids using strong acid, strong oxidant and reduction operation, and simultaneously realizes the one-step preparation of the water-dispersible graphene, and has the advantages of short process flow, high economic efficiency and the like.

The first purpose of the invention is to provide a preparation method of water dispersible graphene, which is to load 1-allyloxy-3- (4-nonylphenol) -2-propanol polyoxyethylene (10) ether ammonium sulfate on the surface of graphene to prepare the water dispersible graphene.

In one embodiment of the invention, the method is to electrochemically load 1-allyloxy-3- (4-nonylphenol) -2-propanol polyoxyethylene (10) ammonium ethersulfate on the surface of graphene, and comprises the following steps: and (3) electrolyzing by taking the aqueous solution of 1-allyloxy-3- (4-nonylphenol) -2-propanol polyoxyethylene (10) ether ammonium sulfate as electrolyte, a graphite sheet as an anode and a metal bar as a cathode to obtain the water-dispersible graphene.

In one embodiment of the invention, the concentration of the aqueous solution of ammonium 1-allyloxy-3- (4-nonylphenol) -2-propanol polyoxyethylene (10) ethersulfate is from 5g/L to 30 g/L.

In one embodiment of the invention, the electrolysis is carried out under the condition of direct current voltage of 5V-20V.

In one embodiment of the invention, the time of the electrolysis is 2h to 8 h.

In one embodiment of the invention, the metal rod comprises a copper rod.

In one embodiment of the invention, the graphite flakes are graphite flakes having a thickness of 0.3mm to 1 mm.

In one embodiment of the invention, the graphite sheet comprises one or more of flake graphite, highly oriented graphite, expanded graphite.

In one embodiment of the invention, the anode and the cathode are placed in parallel at a distance of 1-2 cm.

In one embodiment of the invention, the method further comprises: and (4) after the electrolysis is finished, performing ultrasonic treatment, filtering and drying to obtain the water-dispersible graphene.

In an embodiment of the present invention, the method specifically includes:

(1) preparing an aqueous solution of 1-allyloxy-3- (4-nonylphenol) -2-propanol polyoxyethylene (10) ether ammonium sulfate with a certain molar concentration;

(2) the graphite flake is an anode, the copper bar is a cathode, the two electrodes are arranged in parallel at a distance of 1-2cm, a certain direct current voltage is applied to electrolyze and strip the graphite flake, and after the electrolysis is finished, the graphite flake is ultrasonically stripped for a period of time, filtered, cleaned and dried to obtain the water dispersible graphene.

The second purpose of the invention is to obtain the water dispersible graphene by using the method.

The third purpose of the invention is to provide a polyvinyl alcohol composite material, which is obtained by blending the water dispersible graphene and polyvinyl alcohol.

In one embodiment of the present invention, the method for preparing the composite material comprises: and blending polyvinyl alcohol and the water dispersible graphene through a solution, and drying to obtain the graphene.

In one embodiment of the invention, the mass ratio of the polyvinyl alcohol to the water dispersible graphene is 100 (0.1-3).

A fourth object of the invention is to provide a building or textile material comprising the above-mentioned composite material.

The fifth purpose of the invention is to apply the polyvinyl alcohol/graphene composite material to the fields of textile, medicine industry, food industry, building, wood processing and chemical industry.

The invention has the beneficial effects that:

according to the invention, 1-allyloxy-3- (4-nonylphenol) -2-propanol polyoxyethylene (10) ether ammonium sulfate is loaded on the surface of graphene, and can be adsorbed on the surface of graphene through pi-pi bonds, so that the strong non-covalent bond acting force between graphene oxide and 1-allyloxy-3- (4-nonylphenol) -2-propanol polyoxyethylene (10) ether ammonium sulfate reduces the agglomeration among graphene sheet layers, plays a role of an intercalating agent, and improves the dispersibility of the graphene in water. Meanwhile, the ammonium 1-allyloxy-3- (4-nonylphenol) -2-propanol polyoxyethylene (10) ether sulfate contains relatively multi-oxygen functional groups which can form hydrogen bonds with the lateral hydroxyl groups of the polyvinyl alcohol, so that the mixed solution can form stable and uniform solution.

The number of layers of the graphene prepared by the method is less than 5; meanwhile, the obtained graphene has good water dispersibility, and does not precipitate after standing for 1 month.

The polyvinyl alcohol/graphene composite material prepared by the invention has excellent mechanical property and flame retardant property. Wherein, the storage modulus of the composite material reaches more than 407.2MPa, and the storage modulus is higher than 546.5 MPa; the tensile stress reaches more than 67.08MPa, and the higher tensile stress reaches 80.25 MPa; the peak value of the maximum heat release rate (PHRR) is more than 201W/g, and the peak value is higher to 510W/g. In terms of flame retardant properties: the maximum heat release rate peak value (PHRR) of the polyvinyl alcohol is gradually reduced along with the increase of the addition amount of the graphene, and the maximum heat release rate peak value (PHRR) can be reduced from 510W/g to 201W/g and is reduced by 60.6%.

The polyvinyl alcohol/graphene composite material with high elastic modulus and flame retardant property has wide application prospect in the fields of textile, medical industry, food industry, building, wood processing, chemical industry and the like.

Drawings

Fig. 1(a) is a digital photograph of an aqueous solution of water-dispersible graphene prepared by the method of the present invention after being left for 1 month; (b) is graphite water solution;

FIG. 2 high power TEM image of water dispersed graphene;

FIG. 3 is an X-ray photoelectron spectrum of water-dispersed graphene;

FIG. 4 dynamic thermo-mechanical analysis measured storage modulus curve of polyvinyl alcohol/graphene nanocomposite;

FIG. 5 is a plot of heat release rate as measured by microcalorimetry for polyvinyl alcohol/graphene nanocomposites;

FIG. 6 is a graph showing the change of mechanical properties of composite materials with different contents of polyvinyl alcohol and graphene;

FIG. 7 TEM image of a cross section of polyvinyl alcohol/0.3% graphene nanocomposite.

Detailed Description

In order to further illustrate the present invention, the following embodiments are given to describe the electrochemical preparation of water-dispersible graphene and the preparation method for improving the flame retardant property and mechanical property of polyvinyl alcohol in detail.

In the following examples, polyvinyl alcohol was purchased from Michael reagent, having a polymerization degree of 1700 to 1800, and was soluble in water.